The present invention pertains to a creel structure for supporting warp and weft yarn delivery bobbins in looms.
It is known that creels in general are particular types of racks that are combined with looms in order to support the corresponding warp and weft yarn delivery bobbins, as well as to allow an easy and regular simultaneous unwinding of said yarns from the corresponding bobbins.
In this connection currently used creels comprise a supporting framework consisting of a number of posts and cross-pieces disposed so as to form a parallelepiped configuration. Inside said supporting framework there is a secondary frame comprising two or more cross-pieces with which a number of posts is engaged. Each of the latter is provided with a plurality of support elements adapted to engage the bobbins. The support elements are suitably spaced apart according to a predetermined pitch and extend in opposite directions, towards the parallel and opposed planes defined by the most extending surfaces of the above mentioned parallelepiped configuration.
A plurality of secondary cross-pieces is also located in said planes, each of them exhibiting a number of thread tension devices corresponding each to a support element.
On two of the posts in the supporting framework a number of drawing-in bars is also mounted in cantilevered fashion, each of them being disposed at right angles to a corresponding secondary cross-piece and equipped with a number of horizontal through holes to each of them one of the thread tension devices provided on the secondary cross-piece itself corresponds.
After the above short description it is apparent that the setting up of creels always involves many problems, essentially due to the fact that, as they must be capable of housing a great number of bobbins, creels have an important bulkiness. In this respect currently used creels have proved to be susceptible of improvements.
It is in fact to be noted firstly that the presence of said secondary cross-pieces involves the necessity of disposing the support elements in mutual alignment not only in the vertical direction but also in the horizontal one. That gives rise to the presence of rather important empty spaces between the adjoining bobbins aligned in the vertical direction, which spaces cannot be exploited at all and therefore result in a useless increase in the bulkiness of the corresponding creel. To make the situation worse there is also the fact that, owing to the presence of the above mentioned thread tension devices, the secondary bars must be spaced apart from each other according to a greater pitch than the bobbin sizes would require. In fact, should not this be the case, it would be impossible to replace the bobbins during the operation of the creel, since the same have to pass through the secondary bars above the corresponding thread tension devices.
Currently used creels have disclosed disadvantages also as to the correct delivery of yarns to the respective looms. In this connection it is known that each delivery yarn in the length thereof included between the corresponding bobbin and thread tension device, is subjected to entanglements resulting in the formation of loops, due to the fact that it periodically suffers from spontaneous drops and consequent unwindings from the bobbin itself. So it often happens that a loop may pass through the thread tension device and then come untied downstream of the same. Under this situation the optimum tensioning of the delivery yarn is impaired and, as a result, the complete stopping of the loom occurs due to the intervening of delivery yarn tensioning detecting devices interlocked to the loom itself.